Sweeney-Twin Lake
Sweeney-Twin Lake in Hennepin County, Minnesota has a water quality grade of A (Excellent). Water clarity: 7.5 ft visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 4.8 µg/L.
- Clarity
- 7.5 ft
- Typical in August
- 64°F
- Mean depth
- ~12 ft est.
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- No
Next lake in Hennepin County
Sweeney-Twin Lake is a mesotrophic lake in Hennepin County, Minnesota with an estimated average depth of about 12 feet. Water quality is graded A based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Sweeney-Twin Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-19. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Moderate clarity, visible to about 7.5 ft. Phosphorus level: 22 µg/L. Chlorophyll-a: 4.8 µg/L. Trophic State Index: 48.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.5 ft | Not graded |
| Phosphorus | 22 µg/L | Good |
| Chlorophyll-a (Algae) | 4.8 µg/L | Good |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Sweeney-Twin Lake
Compare lakeside cabins, hotels, and vacation rentals near Sweeney-Twin Lake in Hennepin County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Water Temperature
Sweeney-Twin Lake typically sits around 64°F at the surface in August. Summer average is about 61°F. Usually warmest in Aug (about 64°F) and coldest in Apr (about 43°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 392 field readings (2010–2024) via the EPA Water Quality Portal. See the full Sweeney-Twin Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~12 ft est. |
| Public Access | No |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Minnesota has not published bathymetry for Sweeney-Twin Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Sweeney-Twin Lake
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.169 m/yr | 6 |
| Phosphorus | → Stable | 0 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | +0.07 µg/L/yr | 6 |
EPA Impairment Status
Sweeney-Twin Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN27-0035-01 · Official waterbody report · Matched by proximity (0.07 km)
County Ranking
Ranked #1 of 81 lakes in Hennepin County
Nearby Lakes in Hennepin County
Frequently asked questions about Sweeney-Twin Lake
What is the water quality grade for Sweeney-Twin Lake?
- Sweeney-Twin Lake in Hennepin County, Minnesota has a water quality grade of A (Excellent). Water clarity: 7.5 ft visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 4.8 µg/L.
Is Sweeney-Twin Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Sweeney-Twin Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 4.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Sweeney-Twin Lake?
- Sweeney-Twin Lake typically sits around 64°F at the surface in August, from 392 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Sweeney-Twin Lake?
- No published bathymetric survey covers Sweeney-Twin Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 12 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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Where this data comes from
286 measurements from 3 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA286 samples · 2020–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity, Nephelometric Method
Monitoring station identifiers (3)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder